Global Navigation Satellite Systems (GNSS) is a collective term covering various types of satellite navigation technologies, such as the Global Positioning System (GPS), the European Galileo and the Russian GLONASS. Assisted-GNSS (A-GNSS) enables faster position determination in a mobile wireless device than can be obtained using only the broadcast GNSS satellite data, by providing assistance data from the wireless network, such as ephemeris data, clock corrections, and reference locations. The A-GNSS technology has been standardized in the Open Mobile Alliance (OMA) standard: Open Mobile Alliance, User Plane Location Protocol Candidate Version SUPL2.0: OMA-TS-ULP-V2—0-20091208-C, December 2009.
The Third Generation Partnership Project (3GPP) defines A-GNSS positioning protocols for GERAN (GSM EDGE Radio Access Network), UTRAN (UMTS Terrestrial RAN), E-UTRAN (Enhanced UTRAN) or LTE (Long-Term Evolution), and CDMA (Code Division Multiple Access) networks. The assistance may include the navigation model (orbit and clock parameters), reference location and reference time. In an assisted situation, the receiver does not need to download the navigation model from the satellites, but receives it over the cellular network to significantly reduce the time to first fix and enable accurate positioning in adverse signal conditions.